1. Field of the Invention
The present invention relates to a catheter, especially a flexible illuminating balloon catheter and a method for using the catheter.
2. Description of Related Prior Art
A number of conventional balloon catheters exist in the prior art. Some catheters are used to drain the bladder of a patient during surgical procedure or to treat bladder and/or urethra or prostate conditions, for example.
For example, U.S. Pat. No. 4,248,214 to Hannah et al. (hereinafter “Hannah”) describes an illuminated urethral catheter for draining the urinary bladder while providing circumferential cold illumination of the adjacent urinary tract. Such illumination enables the surgeon to accurately locate the bladder, junction, and urethra without distorting the same so that, for instance, support sutures may be accurately placed adjacent the urethrovesical junction without injury to the urinary tract. The Hannah catheter emanates light outwardly at its distal end through a fiber optic member in all directions (360 degrees) around its circumference. Thus, the Hannah catheter eliminates the need to orient the fiber optic member angularly within the catheter to provide the desired cold illumination of the urinary tract.
The Hannah illuminated catheter requires the light-emitting surface to extend around the entire circumference of the distal end of the fiber optic so that the need to orient the fiber optic is eliminated. This catheter also has a longitudinally movable fiber optic to move the light-transmitting surface along the catheter tube to a desired location. It is noted that Hannah gives an unclear message regarding the intensity of the light emitted from the proximal-most portion 86 as compared to the ultimate distal tip 82. On col. 6, lines 30 to 32, Hannah indicates that the “intensity of the emitted light increases from portion end 86 to tip 82,” i.e., is greater at the proximal end of the emitting area. But at col. 7, lines 50 to 54, Hannah provides that the “intensity of the light emitted from the fiber optic is greatest at the proximal end of abraded portion 84 nearest the light source so that the required high intensity light is provided to illuminate the urethra and urethral-bladder junction.”
Hannah teaches that conventional location of the urethrovesical junction by balloon inflation is to be avoided because they “are, at best, imprecise and distort the urinary tract.” Hannah at col. 8, lines 40 to 47. It is, therefore, desirable to combine illumination with a balloon catheter to investigate in ways not envisioned by Hannah and areas not envisioned by Hannah. It would be desirable to focus all the illumination at a given place in a patient and in a desired direction so that as much light as possible illuminates the place where the surgeon desires and does not illuminate other areas, which illumination decreases the ability of the surgeon to identify the particular area to be investigated.
For example, a common balloon catheter made by RUSCH® and referred to as a Foley catheter is widely used today for treating and draining a patient's bladder. The Foley catheter is shown in FIG. 1 and has a multi-lumen shaft 1 that is disposed in the urethra 10. A balloon portion 3 is disposed at the distal end of the shaft 1, a fluid drain section 4 is disposed at the distal end of the balloon 3, and a curved, distal guiding tip 5 is disposed at the distal-most end of the entire catheter. When placed properly, the proximal-most side of the inflated balloon 3 rests on the interior wall 31 of the bladder 30, entirely blocking off the urethrovesical junction 11 connecting the bladder 30 and the urethra 10. In such a position, the fluid drain section 4 allows continuous drainage of the bladder 30 and the balloon 3 virtually entirely prevents the catheter from slipping out of the bladder. This ideally inserted position is shown in FIG. 1.
It is noted that use of the word “proximal” in the instant application refers to a direction towards the physician, which also corresponds to the bottom of the figures of the drawings.
As such, use of the word “distal” in the instant application refers to a direction away from the physician, which also corresponds to the top of the figures of the drawings.
As used herein, a fluid can be both a liquid and a gas. Exemplary fluids for inflating a balloon 3 are saline, air, or carbon dioxide gas. Exemplary fluids drained by the catheters mentioned herein include urine and blood.
For placement of this catheter in the ideal position within the bladder 30, however, the physician or technician has no visual aid. As diagrammatically illustrated in FIG. 1, the wall 40 defining the urethrovesical junction 11 is very short in the longitudinal direction of the urethra 10. If the technician, nurse, or physician inserts the catheter too far into the bladder 30, no damage occurs from balloon inflation; however, there is a possibility of leakage around the balloon 3, which helps to lubricate the urethra 10 such that gentle proximal movement places the proximal side of the balloon 3 against the urethrovesical junction 11. The bladder 30 can then easily expand and stretch to compensate for the balloon 3. A normal bladder capacity is 400 to 500 cc. A normal balloon capacity is approximately 10 to 12 cc although larger balloons are sometimes used.
The complication occurs when the technician and/or nurse inflates the balloon and in fact the balloon is not in the bladder. If the technician does not insert the catheter in far enough, then the balloon 3 will be subsequently inflated within the urethra 10—a condition that is common and, not only is it to be avoided at all costs, is a frequent cause of bladder infections created during a hospital or clinic visit. Infections arise because inflation of the bladder 3 inside the urethra 10 causes the urethra 10 to stretch too far. Even though the urethra 10 is a flexible tube, it has limits to which it can be safely stretched from within. Almost every balloon catheter has an outer diameter/circumference that well-exceeds the safe stretching limit of the urethra 10. Therefore, if the balloon catheter is not inserted far enough, inflation of the balloon 3 will cause serious injury to the urethra 10. This is especially true with elderly patients who have urethra 10 that are not as elastic as younger patients. Tearing of the urethra 10 in this way causes bleeding and allows bacteria to enter into the bloodstream at the tear site, thus causing the subsequent bladder infection.
In such a case, the balloon expands and tears the surrounding membrane called the mucosa. Tearing of the urethra 10 in this way causes bleeding and allows bacteria to enter into the bloodstream at the tear site, thus causing the subsequent bladder infection. Significant bleeding can become life threatening. The urethra can normally dilate several millimeters; however, when the balloon is inflated, this dilation is usually several centimeters.
Over 96 million indwelling catheters are sold on an annual basis. Twenty four million catheters are sold to hospitals in the U.S. There are numerous complications associated with those catheters that need to be prevented. These complications are responsible for increases in hospital stays, excessive bleeding, mortality, as well as morbidity. This also causes an increased expense and burden on the already-stressed health care system.
The complications result from several different mechanisms. First, and probably most common, is improper placement of the catheter. Because of the unique anatomy of the male urethra, placing a urethral catheter for urinary drainage can be difficult. A problem arises when the physician, technician, or nurse thinks that the catheter is actually in proper position. The proper position for the catheter is with the balloon being in the cavity of the bladder and the tip distal to the balloon is used to drain the bladder cavity.
Life threatening bleeds, especially in patients who are anticoagulated, can and do occur. Also when the urine is infected, as in immunocompromised patients and the elderly, the bacteria, then, get into the blood stream and can cause serious infections called sepsis, which frequently can lead to death. If the patient survives the initial trauma, then long-term complications, such as strictures, can and usually do occur. Strictures are narrowings within the urine channel and usually require additional procedures and surgeries to correct.
Other mechanisms of catheter-induced injuries are inadvertent manipulation of the tubing or dislodging of the balloon because the balloon is pulled due to a sudden jerk or tension. This usually happens when the patient is ambulating or traveling from the bed to the commode or bathroom. The tubing may inadvertently become fixed while the patient is still moving, at which time a sudden jerk is imparted upon the balloon and pulls the balloon into the urethra causing severe pain and bleeding. Injury caused by the improper, inadvertent, and/or early removal of an inflated balloon catheter is referred to as iatrogenic injury (also referred to as an in-hospital injury).
Yet another scenario occurs when the patient deliberately pulls on the catheter, thereby causing self-induced pain and injury to the urethra. This commonly happens in confused patients, for example, patients in nursing homes who have a disease or cognitive dysfunction problem, such as Alzheimer's disease, or other diseases that make the patient unable to understand the necessity of having a catheter. Confusion occurs when the patient has a spasm causing a strong urge to urinate and pain. During the spasm, the confused patient often tugs and pulls on a catheter, which results in injury.
These types of injuries are not limited to males and also cause severe damage to the female bladder and urethra. The injuries can also occur post-surgically, which makes the damage even more severe. One common situation where injury is cause is when the patient is medicated with morphine or other analgesics that render the patient confused and unable to make rational decisions. These injuries have been well documented and are not limited to adults. Numerous injuries are documented in pediatric patients.
Usually, it takes time to make a diagnosis of patient-caused catheter injury. Immediately after diagnosing the injury, a technician needs to deflate the catheter. However, once the urethra is torn, replacing the damaged catheter with another catheter is quite difficult and, in fact, exacerbates the injury. Sometimes, the patient has to be taken to the operating room to replace a urinary drainage tube once this scenario occurs. Because catheters and leg bags are now used routinely in certain situations during home health care, this scenario is not limited to hospitals and occurs at nursing homes or the patient's home.
Most of the recent catheter technology has been focused on reducing urinary tract infections that are caused by catheters, injuries that are usually the most common catheter-related complications.
A balloon catheter made by TherMatrx, Inc. is used to treat Benign Prostatic Hyperplasia by treatment with THERMATRX® Dose Optimized Thermotherapy, a minimally invasive procedure performed in a urologist's office that uses heat delivered through a microwave antenna. A urethral catheter containing the microwave antenna is passed through the urethra and prostate gland and is secured by a balloon at the tip of the catheter that passes through the urethral sphincter. Localized microwave energy is delivered at a temperature high enough to relieve BPH symptoms, including difficult, frequent, or urgent urination. Features of such a catheter are also diagrammatically illustrated in FIG. 1. The catheter differs from the standard Foley catheter by the addition of a radiation coil 2 disposed at a distal end of the shaft 1 proximal to the balloon 3. When placed properly, the radiation coil 2 is immediately adjacent and/or inside the prostate 20 and the proximal-most side of the inflated balloon 3 rests on the interior wall 31 of the bladder 30, entirely blocking off the urethrovesical junction 11. In such a position, the prostate 20 can be directly treated with the radiation coil 2. This ideally inserted position is shown in FIG. 1. In use, correct placement of this catheter in the ideal position within the bladder 30 and near the prostrate 20 is the same as the Foley catheter—it is difficult and gives the physician or technician no visual aid. If the balloon 3 of the THERMATRX® catheter is not at the urethrovesical junction 11, then the heating element 2 would not be in the proper position and subsequent heat damages an undesired area that can cause unintended injury.
In a conventional balloon 3, the balloon 3 has a substantially constant balloon wall thickness. The balloon 3 is fixed to the outer surface of a fluid drainage line (not illustrated in FIG. 1) and is not intended to be removed therefrom or to burst thereon unless an extraordinary amount of inflation occurs. If such an event happens, the material of the balloon will open at a random location based upon the microscopic fractures or weaknesses in the material itself. Such a tearing event is not supposed to occur under any circumstances during use with a patient.
Prior art catheters are not constructed to prevent tearing of the urethra during a catheter implanting procedure and are not constructed to break in any predefined way. Accordingly, it would be beneficial to provide a balloon catheter that does not inflate past the tearing limit of a urethra and breaks in a desired, predefined way under certain conditions.
In a conventional balloon 3, the balloon 3 has a substantially constant wall opaqueness—it is either fully transparent or it is semi- or fully-opaque (due to the natural properties of the balloon material). Accordingly, it would be beneficial to provide a balloon catheter that has differently placed regions of reflectivity and/or opaqueness to direct illumination from within the balloon catheter in a desired direction.